Abstract:
The Super-modes are Fourier limited FEL
micro-pulses
predicted by Dattoli and Renieri in 1980. The
OK-4
FEL at Duke, operating in the wavelength
range from 193.7 nm
to 730 nm, was the first to observe the
Super-modes in a storage ring FEL in 1996.
Since 1996, the
up-graded diagnostics and improved control of
the RF frequency allowed generation of
Super-modes on a
regular basis and systematic study of them. The
Gaussian FEL micro-pulses with 1.3 ps RMS
duration and
Fourier limited RMS linewidth were generated in
1998-1999. In this paper we present the
results of our
studies and the comparison with theoretical
predictions.
We also present practical criteria for
operating SR FELs
with Super-modes.